The invention relates to an anti-fracture fan structure, particularly to an anti-fracture fan structure that has a plurality of ribs in predetermined shapes to prevent the fan from fracturing due to heat expansion.
A fan is widely used to dissipate heat generated by electrical devices such as desktop computers or notebook computers. FIG. 1 is a schematic illustration that shows a conventional fan structure. Referring to FIG. 1, the fan includes a hub 11 and a shielding-can 12. The hub 11 has an inner surface 111. A plurality of blades 112 are arranged around the hub 11. A plurality of ribs 113 are provided around the inner surface 111.
The hub 11 is usually made of a material such as plastic or resin. The shielding-can 12 is usually made of a metallic material that has a high strength property, and is mounted inside the hub 11 by press fitting in order to prevent a ring-shaped magnet (not shown), that is situated around the inner surface of the hub 11, from being deformed. Thus, the magnetic leakage phenomenon can be avoided.
The ribs 113 are useful for mounting the shielding-can 12 into the hub 11 and preventing the hub 11 from being fractured.
In general, the fan starts operating at a lower temperature. The temperature of the fan gradually rises owing to the heat energy generated from the fan or the heat energy transferred from a heat sink (not shown). For example, it is possible that the temperature of the fan rises from xe2x88x9210xc2x0 C. to 50xc2x0 C.
However, the hub 11 and the shielding-can 12 have different heat expansion coefficients because the hub 11 and the shielding-can 12 are made of different materials. For example, the heat expansion coefficient of a PC (poly carbonate) material constituting the hub 11 is about 2.5xc3x9710xe2x88x927 in/in xc2x0F., while the heat expansion coefficient of a metal material constituting the shielding-can 12 is about 6.5xc3x9710xe2x88x926 in/in xc2x0F., which is 26 times as large as that of the PC material. As a result, if the fan is subjected to heat energy, the shielding-can 12 expands faster than the hub 11, causing the hub 11 to fracture from the pressure of the expanding shielding-can 12.
To overcome the above drawback, it is therefore an object of the invention to provide an anti-fracture fan structure in which the hub is not easily fractured by the pressing force of the shielding-can when the fan expands.
To achieve the above objective, there is provided an anti-fracture fan structure including a hub, a plurality of blades, and a plurality of ribs. The hub has an inner surface formed inside and encircling it. The plurality of blades are arranged outside and around the hub. The plurality of ribs projects from the inner surface of the hub into the inside of the hub. Each of the plurality of ribs is not perpendicular to the inner surface of the hub.
Furthermore, the anti-fracture fan further includes a shielding-can situated inside the hub and in contact with the plurality of ribs.
Moreover, the hub can be formed of a plastic material and the shielding-can can be formed of a metal material.
The ribs can be easily warped when the shielding-can expands. Therefore, the hub is not easily fractured by the expansion of the shielding-can when the fan expands with heat.